Observations and Theoretical Analysis of Lightcurves of Natural Satellites of Planets

We present the results of photometric observations of Saturn's seventh satellite Hyperion and four other planetary satellites: Saturn's moon Phoebe and three Jovian satellites Himalia, Elara, and Pasiphae. The observations have been conducted from September, 1999 to March, 2000, and during September–October, 2000. Analysis of periodic variations in Hyperion's lightcurve was performed. The lightcurve was modeled using the software package developed for calculating the rotational dynamics of a satellite. Our data generally indicate that over the period of observations Hyperion was in the chaotic mode of rotation.     

Microshower Structure of the Meteor Complex

Meteor radar observations of ionized trails in the Earth’s atmosphere provide observations that do not depend on weather conditions and time of day and provide good statistics for analysis. Further development in the new quasitomographic analysis of the goniometric data of the Kazan meteoric radar has revealed a number of very weak meteoric streams with rates of more than 5–6 meteors per day. In addition to the known large meteor showers, we have found up to as many as 1000 small showers per month that we have named microshowers. We shall operationally define a microshower as the minimal meteoric stream which can be detected with the Kazan meteoric radar while quasitomographic procedures of processing interferometer data are used.     

Orbital structure of the meteor complex according to radar observations in Kazan. 1. Apparent distributions of aphelia

The results of an analysis of the orbital structure of the meteor complex accessible for radar observations at northern midlatitudes are reported. Experimentally, the study is based on the long-term monitoring of the influx of meteor matter into the Earth’s atmosphere performed with the meteor radar of Kazan State University starting from 1986. The study uses a discrete quasi-tomographic method to measure the radiants and velocities of meteor showers based on goniometric data of the meteor radar and diffraction measurements of meteor velocities. The discretization of the detection environment—in particular, in terms of velocity—is shown to result in no substantial loss of measurement accuracy. The error of the measured velocity of the shower does not exceed 1.5 km/s for a standard deviation of a single velocity measurement equal to 3 km/s. Microshower representation is used with microshowers either representing the correlated part of the sporadic complex or being partial streams of major and minor showers, or fragments of the dust environment of minor bodies passing by Earth or falling onto it. The data of measurements made over the entire annual cycle are used to construct combined maps of the distribution of the observed 2263 microshowers (a total of 22 604 orbits) by their inclination, aphelion distance, and longitudes of the ascending nodes of their orbits. The observing conditions are shown to have a significant effect on the parameters of the distribution of aphelion distances for different months, and the corresponding distributions for prograde and retrograde orbits are shown to differ fundamentally. A specific feature of such distribution maps is that they allow uniform representation of both meteor showers and irregularities of the sporadic complex.     

Geochemical features of Paleozoic Au–Ag epithermal deposits (Northeastern Russia)

The geochemical features and conditions of formation of the Paleozoic epithermal Au–Ag mineralization in the pre-accretion Kedon (D_2–3) volcanoplutonic belt located within the Omolon craton terrain are described. The new data on the composition and contents of trace and rare-earth elements (REEs) in igneous ores of epithermal deposits is provided. The elevated grades of a wide range of trace elements as compared to the average values of the upper crust have been identified.